Remote antenna tuning indicator



J. A. EDINBORGH REMOTE ANTENNA TUNING INDICATOR i April 25, 1950 Filed Deo. 14, 1945 J` ARTHUR EDINBORGH Patented Apr. 25, 1950 i ,srrAr Ass ears-Nr ofFFI-cs 255043,67 REMOTE ANTENNA 'ruiNGiNnIoA'roni l: 'Julius 'ArthurjlEdinborgli,,Washiltom `App1iannneember 14, 1945;senainafcssglsr v claims-.f (or 250g- 1n (Grantedeundef: the act bf2-March: as issaaslv amendedllA'prl. 1928; 32010.r G.- .757).-

f 'I'his; inventionv relatesn to ga, 4remote antenna ,tuning I system;-A and, more partgicularly, to` the remote :tuningoeV ianantenna matching section to iai transmission linerby useiof. an electronic `indicating-device.: y N V y y In manyl installagtions;ci radio transmitters-itis necessary to locate,-theantenna some position removed from the immediate location of `the transmitterrthus-necessitating the `use of a trans- .mission linefto .feed radio frequency gpower,` from the transmitter to theantenna This, however,

`introduces additional problems since it is necessary to match the-ftransmitteroutput to the char- ;acteristic-.impedance off.the transmission line,

the-transmission line, in turn.tQ the an.-

`-tenna inforder to obtain maximum power trans- The inyentiondescribed herein provides means Y .for tuning j the Amatch-ing .section ina remote Yairlltenna system from A,thetransmitter position, and I indicatinggmeans to show.when a match `has been the antenna matching section,4 usually located at the base of-the antenna'.

Another object of theinyention is toyprovide meansffforitunine the antenna/i011 full pweriof `if'elesred, reduced power. .I

Still other and further objects and featuresV of this invention will be apparent from the following specication and drawing, showing an eX- emplary embodiment of the invention, in which the gure is a schematic wiring diagram of the remote antenna tuning system, showing in block, the antenna matching section, and the tuning console with its important controls.

Equal value resistors I, 2 and 3, together with fr the antenna matching section 4, make up the four arms of a conventional bridge circuit. The

antenna matching section `ll is connected to the bridge through contacts 8 and 9 of relay it. Radio frequency energy is fed from the transmitter 25 to the antenna matching section d through coaxial feeder cable II and through contacts 6 and 1 of relay I0. The antenna matching section t is tuned remotely from the tuning console i2 by some appropriate means such as a servo-system as indicated in the drawing by the dotted line I3. Radio frequency energy is fed Vfrom transmitter 25 to the bridge through coaxial cable I i and contacts 5 and 6 of relay I0. The tuneoperate switch I4 is connected in series with relay 56 `liland:,apsourc'e. oifr'elay voltage, and is` located inmthe..,tulning: console I2.`, Resistors I5, Iii` and I Il' arecseries ',connected; across: the bridge attthe junction or; resistors 2; and. 3,' and; resistor; I .Y and contact sofrelaysili. Across resistor:.I6;isconnected a;.diode:vacuum tube: lswith a condenser I9 intitsncathode; leadl'.: vlThe .radio-1 frequency AchokexZljiscon-nected from.the cathode-.of tube IB toimilliammeter 23zandtn'condenserr2ll. The remainingv plate of condenser "20 is? grounded. Radio requencyrchokegf 2; I'is connected fromxthe -iunction o-fsresistors;I i6- and I1 tcground.` Meter .23 .ist in series: with: meter; 2,4; the; latter being located inthe tuning-rconsolev I 2,l anidltheground fcircu-it is,coinpletedlatrthesaiorementionedtuning console; 1 j o The operation of this invention; willbe clearly understood bygreierringf tothe .guref and @tracing .through the; process:` required. for remote tuning.

-1-'J`he,tune-operateswitchV I4 inthe tuning console,

which; is locatedat the; transmitter, is switched to Tune position. Relay I il in the remote' unit isenergized .and contacts i 5: and lqcf relay Iii `are lmada;,enabling T,the radio, frequency, energy cou- ,pledffromfthe transmitter to the-remote unitgby :coaxialicable IIV 1;o--be ;app1iedto vthe bridge: The energize-tion of relay I 0 alsocloses contacts and 9 which cause the antenna match-ing section; ligand' the antenna to .be inserted as one arm of; the,b ridge. Resistors I;2, and 3 are of the same value asv the limpedance ofy coaxial transmission line- Il; ,'Iherefore, it` is desirable vto .tune-,theaantenna-matching.,section 4 to this common impedance by means oi a servo-mechanism I3 from the tuning console I2. To determine when a balance has been reached resistors I5, I6, and I! are connected across the bridge, diametrically opposite to the energizing connection. If the bridge is initially unbalanced an alternating voltage of radio frequency will appear across resistor I6. The vacuum tube I8 in series with condenser I9 will pass this alternating Voltage on half cycles only resulting in a rectified voltage which appears across condenser I9. The rectified Voltage on the condenser I9 will be positive at its cathode connection and will pass through radio frequency choke 2l and ow through meter 23 and meter 24 to ground, giving an indication. When the antenna matching section, as controlled from the tuning console, is adjusted -for minimum current in either meter 24 or 23, the bridge is balanced and the antenna is matched to the transmission line II. The combination of condensers I9 and 20 and radio frequency chokes 2| and 22 forms a high impedance lter for radio frequencies while passing direct current easily. This network also provides a. high impedance path between the meter and the bridge circuit, permitting the use of a ground return from the tuning console meter 24 and thereby eliminating the need for an eXtra return lead.

Resistors I, 2 and 3 should be non-inductive and of a high enough power'rating to carry the entire power output of the transmitter. Resistors I5 and II should also be of a non-inductive type and of equal value, being of such a magi nitude as t0 produce the correct sensitivity for a given transmitter power output. If it were desirable to tune the transmitter 0n reduced power, resistors I, 2, and 3 could have their wattage ratings reduced in accordance, and resistors I5 and I1 could also be reduced to increase the sensitivity.

duced t0 zero.

If the tune-operate switch III at the tuning console I2 is switched to the operate position,

-relay IB will be deenergized and the radio irequency power from the transmitter will be coupled through coaxial transmission line and through contacts 6 and 1 of relay IG into the antenna matching section and thence to the antenna. It is seen that that bridge is entirely out of the circuit when relay I0 is deenergized.

Where installation permits a series resistor contact 5 of relay I 0 and the junction of resistors l and 2, 0r a bleeder resistor could be connected from contact 5 to ground and the aforementioned junction tapped to some low voltage on the bleeder, permitting the use of low power resistors in the bridge circuit.

While there has been described above-a specic embodiment of the invention, itY should be understood that other adaptions thereof may be'v made without the departure from the spirit of the invention. The invention described herein may be manufactured and used by or for the Government 0f The extreme vsensitivity is reached when the resistance of resistors I5 and I1 are remay be inserted in the energizing lead between 'the transmitter t0 said antenna system, an impedance network operative to form a bridge cir- 0 Number cuit upon the insertion of an impedance equal t0 the transmission line impedance, switching means operative to insert said antenna system into said impedance network to thereby form a bridge circuit and to energize the bridge circuit from said transmission line, means controlling said switching means from said transmitter, indicator means operatively connected to said bridge circuit to indicate the condition of balance Y thereof, and means for adjusting said impedance matching section to obtain a balance in said bridge.

2. In combination; a transmitter, an antenna system including an impedance matching section therefor, a transmission line connecting the transmitter to said antenna system, an impedance network operative to form a bridge circuit upon insertion of an impedance equal Yto the transmission line impedance, switching means operative to insert said antenna system into said impedance network to thereby form a bridge circuit and to energize the bridge circuit from said transmission line, indicator means operatively connected to said bridge circuit to indicate the condition of balance thereof, and means for adjusting said impedance matching system to obtain a balance in said bridge.

3. In combination; a source 0f radio frequency power, a transmission line connected to the output of said source of power, an adjustable impedance load for said transmission line, an impedance network operative to form a bridge circuit upon insertion of, an impedance equal to the transmission line impedance, switching means operative to insert said adjustable impedance load into said impedance network to thereby form a bridge circuit and to energize the bridge circuit from said transmission line, indicator means operatively connected to said bridge circuit to indicate the condition of balance thereof, and means altering said adjustable impedance load to obtain a balance in said bridge.

JULIUS ARTHUR EDINBORGH.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Name Date Bohannon May 14, 1940 Holmes Nov. 4, 1947 

